I am not sure about using push notifications at the first place.
Google chrome and all other browser are phasing out 3rd party cookie anywhere in next year or two. Which means most of the users will no longer receive notification. Also opt-ins and other things will change.
Beleive it or not push notifications are abusive and not a great user experience. Who likes waking up to their phones with 30-40 notification or getting pinged for an offer again and again.
It might not be a good thing for website. It might work with apps, but not so good with a website.
Sorry, I have no idea about it.
Please ask to provider where you are migrating.